Riveting tool for use with mandrel-equipped blind rivets



April 7, 1970 E. HORNUNG 3,504,519

RIVETING TOOL FOR USE WITH MANDREL-EQUIPPED BLIND RIVETS Filed April 22, 1968 3 Sheets-Sheet 1 E. HORNUNG April 7, 1970 RIVETING TOOL FOR USE WITH MANDREL-EQUIPPED BLIND RIVETS Filed April 22. 1968 3 Sheets-Sheet 2 NGI i um@ om.. N. w nQ N- oN FN nm., mp uo" m N m /X/ am. m..

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April 7, 1970 E. HORNUNG 3,504,519

RIVETING TOOL FOR USE WITH MANDREL'EQUIPPED BLIND RIVETS Filed April 22. 1968 5 Sheets-Sheet 3 United States Patent O U.S. Cl. 72-391 14 Claims ABSTRACT OF THE DISCLOSURE A riveting tool including a housing having a retracting element which is bored for the passage of the mandrel of a blind rivet thereinto. The housing also includes a nosepiece through which the mandrel passes, and a clamping device for engaging and holding said mandrel. A power driven spindle is rotatably mounted in the housing and its leading end projects freely into a bore of corresponding size in the retracting element. The spindle is provided on its exterior surface with saw-tooth threads. A sliding element provided with corresponding female threads is mounted for radial movement into engagement with the threads on the spindle. As the spindle is rotated the sliding element moves longitudinally away from the clamping device exerting a longitudinal force on the axis on the mandrel of the blind rivet so as to set the rivet in place BACKGROUND OF THE INVENTION This invention relates to a riveting tool for the insertion of mandrel-equipped blind rivets successively into rivet holes, and the subsequent setting of each rivet by withdrawing the mandrel and breaking the same at a weakened zone, thereafter withdrawing the remainder of the mandrel from the upset, anchored rivet. It is essential that riveting tools of this character shall provide an unequivocally -firm gripping of the mandrels, and shall apply a relatively powerful pull thereto, thereby affording a firm setting of each individual rivet.

It is known to use hand riveting tongs, and even hydraulic riveting tools, with the aim of fulfilling these requirements. Working with hand riveting tongs is extremely laborious and time-consuming and is therefore only undertaken in special cases. Riveting using hydraulic riveting tools does not require any heavy physical effort, but nevertheless takes up a great deal of time for upsetting the rivet and withdrawing the remainder of the mandrel because the oil-driven piston only operates with a considerable amount of inertia. Hydraulic welding tools are moreover of extremely complicated construction, are expensive, and are prone to breakdown, because they have to develop and control a very high oil pressure.

It is known moreover to combine the actual tool and its clamping device with the piston/cylinder unit into va form of pistol which is coupled to the oil reservoirusually activated by compressed air-through a high pressure hose and an operating conduit, which usually is controlled by compresed air, that is to say through a power hose. Such equipment is obviously expensive and is also not easy to handle because of the high pressure hose, quite apart from the fact that the working rate is much too slow in this environment.

Accordingly, it is an object of this invention to provide a small, light and handy riveting tool which involves only a small power consumption, but which permits the insertion and upsetting of blind rivets and the extraction of the mandrel remainders without effort and at a sub- 3,504,519 Patented Apr. 7, 1970 ICC stantially higher operating speed, and which can be made at a competitive price because of its simple and robust construction.

SUMMARY Generally speaking, the invention comprises a riveting tool for use with mandrel-equipped blind rivets including a housing in the form of a sleeve which tapers conically at its leading end. Mounted in the housing is a retracting element which is bored for the passage of the mandrel thereinto and adapted for power driven mandrel-withdrawing movement axially in said housing. A nosepiece arranged at the leading end of the housing is bored for the passage of a mandrel and includes a clamping device for engaging and holding said mandrel during the rivet setting operation. A spindle is rotatably mounted in the housing towards the driving end thereof and arranged so that its leading end projects freely into a bore of corresponding size in the retracting element. The spindle is provided on its exterior surface at its leading end with threads and includes at the rear end of the spindle a conical bridge piece connecting to a collar of larger diameter. Facilities are connected to the rear of the spindle for rotating the same. A sliding element provides engagement between the retracting element and the spindle `and converts the rotary movement of the spindle into axial movement of the retracting element. The sliding element also has female threads which mesh with the threads of the spindle, the element being movable radially in the retracting element into an engaging position with the spindle threads.

In the preferred embodiment of the riveting tool, a bearing race is secured to the leading end of the spindle for reducing the friction between the spindle and the interior of the retracting element. The clamping device can also be provided with an extension which is of a smaller diameter than the sum of the diameters of two mandrels so as to preclude the loading of the clamping device with a subsequent rivet while the severed mandrel of the preceding rivet is still positioned in the riveting tool.

DRAWINGS Other objects, advantages and 'aspects of the invention will become apparent by reference to the following detailed description and drawings of specific embodiments thereof wherein:

FIG. 1 is a longitudinal section taken through a riveting tool in accordance with the invention;

FIG. 2 is a longitudinal section of a section of a second embodiment of the invention and including a bearing race for reducing frictional effects;

FIG. 3 is a longitudinal section showing a third embodiment of the invention; and

F IG. 4 is a longitudinal section taken through the nosepiece of a riveting tool with portions removed and showing the gripping of a mandrel-equipped blind rivet which is to be set in place by the tool forming the subject invention.

DESCRIPTION OF THE INVENTION Referring rst to FIGURE l, the driving end 1 of a housing 1 of the riveting tool, here shown in cross section, has a clip portion 2 which is disposed on a mounting part 3 of a driving motor 4. This motor 4, which has only been partially shown, is electrically driven, but could alternatively be operated by compressed air or could be a hydraulic motor. It is equipped with a handle, for example in the form of a pistol grip similar tothe motor of a handheld drill.

A shaft 5 emerging from the driving motor 4, is rotated during the operation of the tool, and has a spindle 6 rigidly connected thereto, for example by screw threading.

The spindle 6 is provided at its leading end with threads 7 of saw-tooth shape in cross section, the steep flanks of the teeth being directed towards the shaft 5. At the driving end 1', i.e. at the end adjoining the shaft 5, the screw threads 7 terminate in a conical bridge piece 8 followed by a larger diameter collar 9 on the spindle 6.

The substantially sleeve-form housing 1 tapers conically to the leading end thereof intended to receive a blind rivet R (FIG. 4). A mandrel-retracting element 12 is mounted within the housing 1, this element 12 carrying a clamping device 10. This device 10 and element 12 both taper conically, in conformity with the leading end of housing 1, towards the receiving end. Element 12 is axially slida'ble in the housing against the action of a return spring 11. The retracting element 12 is centrally bored for reception of the mandrel M of the blind rivet R which will be used with the tool and includes a substantial-diameter bore 13 which opens towards the mounting part 3 and is in two steps. The first step 13a is of a diameter which somewhat exceeds that of the collar 9 on the spindle 6, whilst the step 13b which adjoins it in the direction of the clamping device 10 has a diameter which somewhat exceeds that of the threads 7.

The force of the return spring 11 is transmitted to element 12 by means of a plate spring 14 which is apertured with a diameter equal to that of step 13a and adjoins the inner end 12a of element 12. The saw-toothed threads 7 on the spindle 6 extend freely into bore 13 and through the corresponding steps 13a and 13b, and when this retracting element 12 is axially displaced the collar 9 also has a predetermined amount of peripheral clearance.

In the rest position of the retracting element 12, into which it is urged by the return spring 11, the clamping device 10 of this element bears against the inner end surface of a receiving nosepiece 15 which is screwed into the conical tip of the casing 1 and is approximately bored for the passage of the mandrel of a blind rivet R (FIG. 4) to be used with the tool. The clamping device 10, which is per se known, comprises clamping jaws 10a, which are of conical peripheral form and are of conical concavity at their end faces, an adjoining thrust plate 10b which has convex-conical end faces and is also bored for the passage of the mandrel M of the blind rivet R, and a counter spring 10c, which is here under compression. These parts are accommodated in a collet 12b which is screwed into element 12, and is provided with a conical recess in the area of the clamping jaws 10a.

An opening 16 is arranged in the retracting element 12 towards the return spring end 12a, this opening being opposite the threading 7 when the spindle 6 projects into the retracting element in its rest position. Opening 16 is disposed radially in relation to the axis of the bore 13, i.e. to the axis of spindle 6, and a sliding element 17 conforming thereto is displaceable in this opening. This element 17 passes through an axially extending slot 18 in the housing 1 which permits longitudinal displacement of element 12, and terminates externally of the housing in a press button head 17a. Arranged at the opposite end thereof is a segment 17h of female threading conforming in location and shape to the saw-toothed threads 7 on spindle 6. A ball catch 19 is pressed by a compression spring 19C, arranged in a blind hole 19b in the retracting element 12, into cooperating depressions 19a' in the sliding element 17.

In operation, the shaft 5 is set rotating, in this example by the hand-held electric motor 4. The mandrel M of a blind rivet R is pushed through the nosepiece 15 until its rivet head abuts against the outer end of this nosepiece. lt passes into the riveting tool through the clamping jaws 10a of the latter, the thrust plate 10b, the counter spring setting point, and the riveting tool is held rmly against the head of the rivet. Then, by pressing down the push button part 17a of slide element 17, this moves downwards towards the threads 7 of the rotating spindle 6, overcoming the action of the catch 19. When the femaletoothed segment 1717 thereof is brought into coupling engagement with the saw-tooth threads 7 the retracting element 12 is moved in the manner of a traveling nut, axially in the direction of the driving end 1 of housing 1, the sliding element 17, being guided in the slot 18 and preventing the element 12 from turning. In view of the saw-toothed threads used in accordance with this invention, no damaging radial torce components are transmitted to the sliding element 17.

At the same time the conical outer surface of the clamping jaws 10a coact with the conical bore of the collet 12b in the retracting element, and the anti-slip, serrated inner surfaces of the jaws are driven firmly into the material of the mandrel M against the pressure of the counter spring 10c, and the mandrel is thus drawn out of the rivet, in so doing upsetting with its head the corresponding rivet part to form a closing head. When the upsetting operation is finished the mandrel M snaps at its weakened zone and the retracting element 12 continues to move away from the rivet R carrying with it the remainder of the mandrel M, until the sliding element 17, with its nut segment 17b, runs up against the conical bridge piece 8. As a result element 17 is moved radially outwards away from the threads 7 until the ball catch 19a snaps into action. The engagement of the threads 7 with the nut segment 17h is immediately interrupted by this procedure, and the return spring 11 propels the retracting element 12, along with the remainder of the mandrel which was initially firmly clamped thereto, back to the inner end face of the nosepiece 15.

At any rate by the time the clamping jaws 10a strike the inner end face of nosepiece 15, the jaws detach from the remnant of the mandrel with the assistance of the expanding counter spring 10c, and release this piece of the mandrel. The riveting tool has in the meantime been displaced from the inserted and firmly-set rivet, and advantageously the nosepiece 15 is lowered and the piece of mandrel automatically drops out or is extracted by hand, whilst the driving motor 4 can continue to run.

In order to provide sutiicient space in the riveting tool, which is of very compact construction, for the pulling out of long mandrels, the spindle 6 is provided with an inner bore 20 to provide for the maximum mandrel diameters. The individual parts of the riveting tool, such as the spindle 6, the collet 12b of the retracting element with its clamping jaws 10a, thrust plate 10b and counter spring 10c, as Well as the nosepiece 15, are readily replaceable by appropriate loosening of the screw-connected parts thereof. Thus they can readily be changed for other blind rivet mandrel sizes or for the replacement of Worn parts, whilst the replacement of the sliding element 17 is accomplished by simple retraction of the latter from the opening 16 in the retracting element 12 against the force of the catch 19. The ball catch 19a and the catch spring 19e will not fall out during this procedure, being held in the blind hole 19d which accommodates them by appropriate upsetting of the entrance of this hole.

All the parts of the riveting tool preferably are made of steel which is hardened at the particular parts which are exposed to natural wear, with the exception of the plate spring 14, which is conveniently made of light metal to save weight and is also readily replaceable, and the push button part 17a which is made of a plastic material for characteristic and vibration damping reasons and is stuck to the sliding element 17.

The advantages achieved by the invention are to be found particularly in the fact that a small, handy and rapidly-operating riveting tool is obtained instead of a tool which is expensive, liable to breakdown, and is driven by highly compressed pressure duid actuated by an axiallymovable piston, and therefore relatively slow-operating. The new tool is capable of a high rotary driving speed and this, through the agency of a light screw gearing which can be easily and rapidly coupled up by hand and automatically and quickly disengaged at the draw end, converts a small torque in the rotating shaft into the very high axial mandrel-pulling force required of its retracting parts'. The driving motor can continue to turn between the operating phases, and the tool is, in practice, not liable to breakdown or damage because of its simple construction.

The riveting tool described above can be further improved by reducing the friction produced during the mandrel-drawing process and involved by the defiection of the free end of the spindle against the wall of the bore of the retracting element by the sliding piece which presses on the spindle. This involves a certain amount of energy consumption.

Further it is of advantage if provision can be made to avoid any potential jamming of a mandrel-provided blind rivet which is introduced into the nosepiece of the riveting tool for effecting riveting. rl"his could occur if the remnant of a mandrel, which has been broken off in proper fashion does not fall out of the nosepiece when the riveting pistol is temporarily held downwards, or if this piece of the mandrel is not withdrawn by hand. Should this happen, when the next riveting operation is started the new mandrel will press against the remainder of the previous mandrel so that the two will be forcibly seated against one another either in the clamping jaws or within the bore of the withdrawal spindle and the functioning of the riveting tool will thus be impaired.

The riveting tool will be more etiicient for heaviermandrel blind riveting with the same size of motor bccause of the reduction of the internal friction during the draw operation, and the possibility of unskilled operation thereof will be excluded. This is assisted, in accordance with a further feature of the invention (FIG. 2), by the fact that the spindle is provided at the end thereof adjacent the nosepiece, and in front of its saw-tooth threading, with a bearing race the outer ring of which is freely rotatable relatively to the spindle and is of the same diameter as, or of a diameter slightly exceeding that of, the saw-tooth threading of the spindle. Also, the thrust plate is provided with a cylindrical extension at the driving end of the spindle, this extension being f substantially smaller diameter and incorporating a pocket hole which extends centrally from the thrust plate and is dimensioned to accommodate the maximum length of mandrel and the maximum diameter of mandrel which it is anticipated will be used with the tool. The extension passes through the bearing for the counter spring in the retracting element with adequate play and extends into the larger bore with which the spindle and bearing race are provided and into the threaded projection thereof, with adequate, all-round clearance.

As in the embodiment of FIGURE 1, the riveting tool for blind mandrel rivets illustrated in FIGURE 2 comprises the housing 1 which is tapered conically at the leading end and is connected at its driving end 1 to the mounting part 3 of a driving motor 4. Internally it is provided with the spindle 6 equipped with the saw-toothed threads 7, screwed to the shaft 5 of the driving motor 4, and projecting freely into the axially-displaceable retracting element 12. Mounted in this element 12, which is biased by a return spring 11, is the sliding element 17 which is movable radially in relation to spindle 6 and is intended for engagement in the saw-tooth threads 7. Retained in the leading, conically-tapering part of the retracting element 12, which accommodates the mandrel M, and in particular in the collet 12b of this element which is screwed to the latter, is the clamping device which comprises the clamping jaws 10a, the thrust plate 10b with its cylindrical extension 10b', and the counter 6 spring 10c which is applied against the bearing 12' 0f the retracting element 112.

In the rest position of the retracting element 12 the clamping jaws 10a are disposed up against the nosepiece 15 which is bored for passage of the mandrel M, this nosepiece being screwed into the conically tapering end of the housing 1. The thrust plate 10b has the integral extension 10b and is provided with a blind bore 10b" which extends deep into extension 10b' and is of a length corresponding to that of the mandrel M. The bore 10b" is of lesser diameter than the sum of the diameters of two mandrels of the minimum potential diameter. Extension 10b' passes with adequate play through part 12', which forms a bearing for the counter spring 10c, and projects with a like amount of clearance into the bore 20 of spindle 6 which is of corresponding size, as illustrated in FIGURE 1.

To avoid wearing friction between the spindle 6, or its threads 7, against the wall of bore 13, the leading end of spindle 6 is here provided with a bearing race 21 the outer ring 21' of which is of somewhat greater diameter than the outer diameter of threading 7. Because of this the spindle 6 will be able to roll on the wall of the `bore 13b during the coupling up of the sliding element 17 when the mandrel M is being extracted, and the friction will therefore be reduced to a minimum. The bearing race 21, which may for example be a ball bearing race as illustrated, is shrunk t on a cylindrical projection 6' of the spindle 6.

In the construction illustrated in FIGURE 3 the friction which would otherwise be experienced by spindle 6 or its threads 7 is taken by a bearing race 22 which, in the example illustrated, is constituted by needle bearings. The outer ring 22 of this race is made somewhat larger than the diameter of spindle 6 or its threads 7 so that this outer ring 22' can maintain the support of the loaded spindle 6 and thereby greatly reduce the frictional effects on the latter. This `bearing race 22, which is provided with a bore 22a appropriate to accommodate the extension 10b' of the thrust plate 10b, has a screw threaded section 22b by means of which it is screwed into a tapped hole 6a in the spindle 6.

When using the riveting tool, and after the hand-held electric motor 4 has been switched on, the mandrel M of a blind rivet R is pushed through the nosepiece 15 and into the tool through the clamping jaws 10a of the latter and into the blind bore 10b of the thrust plate 10b and its extension 10b' until the head H of the rivet R abuts against the outer end of the nosepiece 15.

During the actual riveting of a mandrel-provided blind rivet, which basically follows the method described in German patent application H 65,428, the extension 10b projects almost wholly into the bore 20 of the spindle 6 (FIG. 2) and into the bore 22a (FIG. 3) of the bearing race 22 and its threaded extension 22b, during the travel of the retracting element 12 in the extracting and breaking off of the mandrel. If the residual piece of the mandrel is not removed from the riveting tool after a riveting operation, no further blind rivet, or a mandrel of the same, can lbe operatively inserted in the riveting tool for a further riveting operation because of the fact that the extension 10b is still clogged with the remainder of the mandrel and because of the available diameter of the blind bore 10b. Any rivet which it was attempted to insert in this way would stop at the very latest at the thrust plate 10b because it would encounter the remainder of the previous mandrel. It will therefore rst be necessary to allow this mandrel remainder to drop out by holding the riveting tool downwards, or to take it out by hand, and only then to insert a new mandrel-provided blind rivet.

The advantage achieved by this invention resides particularly in the fact that the riveting tool is suited for use even with heavy or thick mandrel-provided blind rivets using the same motor power, with simultaneous reduction of wear, so that the length of life of the tool is increased. More than this it is adapted for foolproof operation which, in the event that the remainder of the mandrel is not removed, would lead to damage on account of jamming, and this is made impossible ad initio.

It is to be understood that the invention is not limited to the particular embodiments and features described and shown, but that it comprises any modifications and equivalents within the scope of the appended claims.

I claim:

1. A riveting tool for use with mandrel-equipped blind rivets, including a housing in the form of a sleeve which tapers conically at its leading end, a retracting element which is bored for the passage of a mandrel thereinto and adapted for power driven mandrel-withdrawing movement axially in said housing, a nosepiece arranged at the leading end of said housing and bored for the passage of the mandrel, and a clamping device for engaging said mandrel, said clamping device including a plurality of clamping jaws arranged radially around the axis of the conical leading end of the tool and together defining a conical outer surface, and said jaws being disposed between said nosepiece and a thrust plate subject to the action of a counter spring, the improvement which comprises:

a spindle 6) rotatably mounted in the housing towards the driving end of the latter arranged so that its leading end projects freely into a bore (13) of corresponding size in said retracting element (12) and is provided on the exterior surface at its leading end with threads (7), said spindle further including a conical bridge piece (8) connecting to a collar (9) of larger diameter at the rear end of the spindle;

means connected to the rear of the spindle for rotating said spindle;

a sliding element (17) for providing engagement between the retracting element (12) and the spindle (6) and for converting the rotary movement of the spindle into an axial movement of the retracting element, said sliding element having female threads (17in) which mesh with the threads of the spindle, and being movable radially in the retracting element into an engaging position with the spindle threads,

whereby said sliding element moves rearwardly to set the rivet in place whereupon the conical bridge piece cams the sliding element radially outwardly to disengage its threads from the threads on the spindle.

2. A riveting tool as recited n claim 1, wherein the threads (7) of the spindle have a saw-tooth cross section with the steep flanks of the saw-teeth directed towards the rear end of the spindle.

3. A riveting tool as recited in claim 1, wherein the `sliding element (17) is of circular cross section and is mounted in a conforming circular opening in the retracting element.

4. A riveting tool as recited in claim 1, wherein the sliding element (17) is of quadrilateral cross section and is mounted in a conforming quadrilateral opening in the "retracting element.

5. A riveting tool as recited in claim 1, wherein the spindle (6) is mounted in floating fashion in the tool and is adapted to be connected to the shaft of the driving motor by screw threading at its driving end 6. A riveting tool as recited in claim 1, wherein the sliding element 17) includes a press button part (17a) at its radially outer end and said button part of the sliding element is plastic material adhered to the element.

7. A riveting tool as recited in claim 1, where the sliding element (17 is provided with detent means comprising a depression (17d) formed in the element and a cooperating ball catch biased by a spring (19C) mounted in a hole (19b) in the retracting element (12).

8. A riveting tool as recited in claim 1, wherein the spindle (6) is provided centrally with an internal bore (20) dimensioned to accommodate the anticipated maximum sizes of mandrel diameter and mandrel length.

9. A riveting tool as recited in claim 1, which further includes a return spring (11) and a metal plate (14) positioned between the spring and the retracting element (12) for returning said element after the threads of the spindle and the sliding element are disengaged.

10. A riveting tool as recited in claim 1, wherein the housing includes a clip piece (2) for fastening to a mounting part of the rotating means.

11. A riveting tool as recited in claim 1, wherein the spindle (6) is provided at the end thereof nearest the nosepiece and in front of its threads (7) with a bearing race (21, 22), the outer race of which is freely rotatable relatively to the spindle and is approximately equal in diameter to the threads of the spindle, and wherein the thrust plate (10b) is provided with a cylindrical extension (lflb') directed towards the driving end of the spindle, said extension being of substantially smaller diameter than the thrust plate and provided with a blind hole (10b)` which extends centrally from the thrust plate and is dimensioned so as to accommodate the maximum mandrel lengths and the maximum mandrel diameters of rivets which will be used with the tool, and said extension passing with clearance through the part of the retracting element constituting a bearing for the counter spring acting on said thrust plate, and projecting into a bore in the spindle with all around play.

12. A riveting tool as recited in claim 11, wherein the bearing race (21) is shrunk tit on a cylindrical portion of the spindle.

13. A riveting tool as recited in claim 11, wherein the bearing race (22) is provided with a bore (22a) for the free passage of the extension of the thrust plate, and that the race has a threaded projection (22h) which is screwed into a tapped bore (6a) in the spindle.

14. A riveting tool as recited in claim 11, wherein the blind hole (10b) in said extension (10b) is of smaller diameter than the sum of the diameters of two mandrels of minimum prescribed diameters.

References Cited UNITED STATES PATENTS 2,428,165 9/1947 Ketchum 72-114 2,753,072 7/1956 Mitchell 72-391 3,095,106 6/1963 Morrison 72-391 3,144,156 8/1964 Nouvelet 72-391 3,399,561 9/1968 Martin 72-391 3,412,594 11/1968 Lund 72-391 3,423,986 1/1969 Young.

CHARLES W. LANHAM, Primary Examiner G. P. CROSBY, Assistant Examiner U.S. Cl. X.R. 

